Every primary system on a chip (SOC) in a system needs a Brown-Out Reset or a Power-on Reset circuit inside, which helps initialise the system to a known state at the first application of voltage from a power supply. A ‘primary’ SOC in a system refers to one which does not depend on any other device outside to initialise it. Microcontrollers, power management integrated circuits (ICs), standalone digital signal processing (DSP) systems, etc. fall in this category.
Ultra low power Power-On/Brown-out Reset circuits may be used in microcontrollers that are embedded within a system and often rely on capacitive coupling to detect fast supply ramps and dips. However, this method may not reliably distinguish between transients indicating supply faults and transients within allowed supply range and may therefore issue a reset even when a voltage level from the power supply is proper. Typically, the capacitive coupling path is disabled once Reset is lifted indicating proper supply in order to prevent false resets from occurring due to allowed transient changes in the power supply level.
Other features of the present embodiments will be apparent from the accompanying drawings and from the detailed description that follows.